fix: add missing playlist_length (#110)

* fix: add missing playlist_length

Also convert to TS

* chore: lint

src/parser/classes/EndscreenElement.ts

@@ -0,0 +1,74 @@
+import Parser from '../index';
+import Thumbnail from './misc/Thumbnail';
+import NavigationEndpoint from './NavigationEndpoint';
+import Text from './misc/Text';
+import { YTNode } from '../helpers';
+
+class EndscreenElement extends YTNode {
+  static type = 'EndscreenElement';
+
+  style;
+  title;
+  endpoint;
+  image;
+  icon;
+  metadata;
+  call_to_action;
+  hovercard_button;
+  is_subscribe;
+  playlist_length;
+  thumbnail_overlays;
+  left;
+  top;
+  width;
+  aspect_ratio;
+  start_ms;
+  end_ms;
+  id: string;
+  constructor(data: any) {
+    super();
+
+    this.style = `${data.style}`;
+    this.title = new Text(data.title);
+    this.endpoint = new NavigationEndpoint(data.endpoint);
+
+    if (data.image) {
+      this.image = Thumbnail.fromResponse(data.image);
+    }
+
+    if (data.icon) {
+      this.icon = Thumbnail.fromResponse(data.icon);
+    }
+
+    if (data.metadata) {
+      this.metadata = new Text(data.metadata);
+    }
+
+    if (data.callToAction) {
+      this.call_to_action = new Text(data.callToAction);
+    }
+
+    if (data.hovercardButton) {
+      this.hovercard_button = Parser.parseItem(data.hovercardButton);
+    }
+
+    if (data.isSubscribe) {
+      this.is_subscribe = !!data.isSubscribe;
+    }
+
+    if (data.playlistLength) {
+      this.playlist_length = new Text(data.playlistLength);
+    }
+
+    this.thumbnail_overlays = data.thumbnailOverlays ? Parser.parseArray(data.thumbnailOverlays) : undefined;
+    this.left = parseFloat(data.left);
+    this.width = parseFloat(data.width);
+    this.top = parseFloat(data.top);
+    this.aspect_ratio = parseFloat(data.aspectRatio);
+    this.start_ms = parseFloat(data.startMs);
+    this.end_ms = parseFloat(data.endMs);
+    this.id = data.id;
+  }
+}
+
+export default EndscreenElement;